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title: Indexing Explained
---

## What is an Index?

In Postgres, indexes are database objects that provide a fast way to look up rows in a table. If you
imagine a Postgres table as a book, then an index is like the table of contents. Instead of flipping
through every page to find a chapter, the table of contents stores additional information that can help
readers find chapters faster.

## ParadeDB Indexes

ParadeDB relies on three new index types to power its search capabilities: the BM25 index for full text search,
the HNSW index for dense vector search, and the sparse HNSW index for sparse vector search.

Once an index is created, it will automatically stay in sync with the underlying table data, and
does not need to be re-created unless the table schema changes (for instance, if a column is renamed or deleted).
